1. Field of the Invention.
This invention relates to printing presses and is more particularly directed to a governor for controlling the operation of the positioning control for providing a continuous supply of items, such as sheets of paper, envelopes and the like to the document feeding mechanism of a printing press.
2. Prior Art.
The following examples of prior art relating generally to printing presses and the like were determined in the course of a patentability search for the novel and unobvious invention of this application:
______________________________________ Number Date Inventor Invention ______________________________________ 3,869,116 Mar. 4, 1975 Krocker Decreasing Load Deflection Mechanism 3,961,785 June 8, 1976 Gall Arrangement for Respectively Withdrawing A Single Film Sheet from a Strack of Directly Loosely Superimposed Film Sheets 4,305,577 Dec. 15, 1981 Clay Apparatus for et al. Applying, Varying and Removing a Normal Force in a Shingler Wheel Type Document Feeder 4,524,965 Jun. 25, 1985 Kulpa Envelope Stacking Machine ______________________________________
A typical printing press that may be operable and will benefit from the application of the principles of my invention is comprised of a printing mechanism such as a rotary offset printing apparatus disposed at one end of a frame and cabinet, a paper feeder disposed intermediate the ends of the cabinet or frame and a paper supply table disposed at the opposite end of the cabinet or frame and which is adapted to accept a stack of material to be printed and to maintain the top of the stack at a position whereat the top of the articles stored on the top of the moveable table will be in position to be engaged by the feeder mechanism and transferred from the supply pile to the printing apparatus. The height of the top of the pile of material on the vertically moveable table, therefore, is continuously sensed by a pile height bar, or sensor, that is applied with considerable force to the top of the pile of material to be printed on the top of the table during each cycle of operation of the printing press and where the material needs to be repositioned, so as to be consistantly and efficiently transferred by the feeding mechanism, is adjusted in accordance with the height sensed by the pile height bar or sensor. Continuous operation of the printing press results in the complete depletion of the entire pile of material to be printed without interruption.
When, for example, the material to be printed consists of folded paper, envelopes and/or material that is susceptible of compression when disposed in a pile, considerable interruptions occur by way of jamming or misfeeds due to the distortion of, for example, the ends of a pile of material to be printed as the substantial downward biasing forth of the pile height bar, or sensor, engages the top of the pile to determine the height during each cycle of operation of the printing press. The malfunctioning resulting from this action presents greatly increased labor costs and inefficiency and, when the problem is partially alleviated, as by severely restricting the amount or number of items to be printed that are contained in a stack or pile of material on the supply table, the printing press will still be operable under conditions of lower efficiency because of the increased frequency of attention required by an operator of the printing press to replenish the supply of items to be printed in smaller stacks.